Design Modeling and Simulation Analysis of a Stiffness Enhanced Soft Pneu-Net Actuator

Abstract

Pneumatic soft actuators are widely used in soft robotic systems because of their inherent compliance and smooth deformation. However, their practical application is often limited by low structural stiffness, restricted load-bearing capability, and insufficient tip output force. These limitations become more pronounced in tasks that require stable force transmission or precise interaction with the environment. In response to these limitations, this study proposes a stiffness-enhanced pneumatic soft actuator based on a modified multilayer structural configuration. The actuator integrates chamber layers, a constraint layer, and periodically distributed rigid reinforcement elements. This structural arrangement improves the way internal pressure is converted into bending deformation and external force output, while avoiding excessive local expansion of the chambers. Based on this actuator, a coupled theoretical model is developed to describe the relationship between internal pressure, bending angle, and tip force. The model considers both the hyperelastic behavior of the silicone material and the geometric constraints introduced by chamber deformation. Finite element simulations are performed to examine the actuator’s mechanical response under different pressure inputs. This effect becomes evident at higher pressure levels. Both free-bending behavior and tip contact force generation are analyzed. The simulation results follow the same trends as the theoretical predictions, and the overall deviation remains below 10% across the investigated pressure range. The agreement shows that the model reflects the main mechanical response. Compared with a conventional pneumatic soft actuator, the proposed design achieves higher stiffness and larger tip output force, while maintaining compliant motion and smooth bending behavior. The actuator structure and model may serve as a useful basis for pneumatic actuator design in force-demanding tasks.